Despite tremendous advances in the care of critically ill patients, trauma remains a major health problem within the US. Mortality and morbidity associated with trauma are due in part to secondary conditions triggered by the initiating insults, such as sepsis, and acute respiratory distress and multiple organ dysfunction syndromes. While the precise etiologies of these conditions are unknown, they likely result from an exaggerated inflammatory process. Several factors, including initiating insult, environment, sex, age, and genetic make up, have been proposed to regulate the inflammatory process, thus, determining the final outcome of clinically ill patients. A genetic contribution to the inflammatory process has recently been indicated in murine models. Several quantitative trait loci (QTL) for cytokine plasma levels during inflammation have been mapped after injection of bacterial lipopolysaccharide (IPS). In particular, a QTL on mouse Chromosome 8 was found for LPS-induced interleukin (IL) 10. A candidate gene in this region, macrophage scavenger receptor 1 (Msr1), has emerged. The first aim of this investigation is to confirm the role of Msr1 during inflammation. The second aim is directed at mapping additional genes that regulate the inflammatory process in a more clinically relevant murine model of sepsis, cecal ligation and puncture. QTL will be mapped using recombinant inbred mouse strains and confirmed using consomic and congenic mice. Candidate genes within these loci will be identified by a combination of bioinformatics and positional cloning. Thus, the overall objective of this proposal is to identify genes that contribute to the inflammatory responses in experimental mouse models. Genes regulating the degree of inflammation in mice are likely to lie along the same pathways as those influencing human disease and may ultimately provide a basis for identifying individuals at risk for exaggerated inflammatory conditions.